Reproductive management of postpartum cows

High reproductive efficiency in the dairy cow requires a disease-free trans ition period, high submission rates to AI and high pregnancy rates per serv ice. A key risk factor that causes increased incidence of metabolic disease is low negative energy balance (NEB) in the periparturient and early postp artum periods. Low NEB decreases LH pulse frequency, growth rate and diamet er of dominant follicle (DF), IGF-I, glucose, insulin concentrations and in creases GH and certain blood metabolites; these effects result in greater l oss of body condition score (BCS) and a higher percent of anoestrous cows i n the herd. It is important to decrease the incidence of metabolic disease by achieving high dry matter intake (DMI) and minimising the period of NEB after calving. Thus, nutritional management of the cow in the transition pe riod has a crucial role to play in improving reproductive efficiency, becau se acute nutritional deprivation of heifers has immediate deleterious effec ts on follicular growth and ovulation. To obtain high submission rates, it is necessary to decrease the incidence of anoestrus and to have good oestro us detection rates. Pregnancy rates per service are affected by a variety o f factors. NEB can have deleterious effects on the follicle or the corpus l uteum (CL) by decreasing IGF-I concentrations and steroidogenesis. High pro tein diets fed to postpartum cows leads to increased blood urea and lower f ertility. Although the mechanism is not clear, the practical implication of feeding the appropriate level of crude protein in the diet is clear. Thus, a coordinated management approach involving herd managers, nutritionists a nd veterinarians is required to obtain high reproduction efficiency in dair y cows. (C) 2000 Published by Elsevier Science B.V. Ail rights reserved.